JP2021086927A - Hybrid-type superconducting bulk magnet device and magnetization method thereof - Google Patents

Abstract

To provide: a hybrid-type superconducting bulk magnet device which can generate a magnetic field larger than an applied magnetic field, moreover can persistently generate a magnetic field larger than an applied magnetic field even after the applied magnetic field is zeroed, and, in addition, can reliably and individually control the temperatures of a cylindrical bulk superconductor and a bulk superconductor lens that are made of the same material, at low cost by one cooling device; and a magnetization method thereof.SOLUTION: In a hybrid-type superconducting bulk magnet device, a bulk superconductor magnetic lens, which is formed by butting a pair of superconducting bulks made of the same material as a cylindrical bulk superconductor that comprises REBaCuO (RE represents a rare earth element or Y), is arranged at the internal center of the cylindrical bulk superconductor; one cooling device for cooling both the bulk superconductor magnetic lens and the cylindrical bulk superconductor is provided; a heat leak member for delaying the cooling of the cylindrical bulk superconductor is arranged between the cooling device and the cylindrical bulk superconductor; and temperatures of both the bulk superconductor magnetic lens and the cylindrical bulk superconductor are individually controlled.SELECTED DRAWING: Figure 6

Description

The present invention relates to a hybrid superconducting bulk magnet device that generates a high magnetic field using a superconducting bulk and a magnetizing method thereof.

Recently developed superconducting magnets using superconducting bulk are more compact than superconducting coil magnets and are suitable for applications that generate a large magnetic field in a relatively small space.

As a superconducting magnet using a superconducting bulk, a bulk superconductor magnetic lens that uses the magnetic lens effect to converge the magnetic flux at an appropriate position in the direction of inducing the magnetic flux has been proposed (Patent Document 1 and the like).

FIG. 1A shows an example of a superconducting magnet device using a conventional bulk superconductor magnetic lens. This superconducting magnet device 1 is composed of a bulk superconductor magnetic lens 2 formed by abutting a pair of superconducting bulks, and a magnetizing magnetic field (applied magnetic field _Bapp ) is applied by a magnetizing superconducting magnet 3 arranged outside. It has become so. For example, GdBaCuO is used as the superconducting bulk, and NbTi is used as the superconducting coil.

In this superconducting magnet device 1, the magnetic field created by the superconducting magnet 3 for magnetizing is converged by a bulk superconductor magnetic lens 2 provided inside by using a magnetic shield effect, and the magnetic field amplification factor (ratio of the generated magnetic field to the applied magnetic field). Is to generate a _{high magnetic field B c} larger than 1 as shown in FIG. 1 (b). At present, under the external magnetic field _B app = 8T, the magnetic field convergence 12.4T bulk superconductor magnetic lens within 2 is realized (Non-Patent Document 1).

However, in such conventional superconducting magnet device 1, since the magnetic field focusing effect of the magnetic lens effect when the external magnetic field B _app zero is lost, the state of magnetizing the superconducting magnet 3 is energized (Fig. 1 (b ) Is only valid (indicated by the dotted arrow).

Therefore, in Patent Document 2, the present inventor can continuously generate a magnetic field larger than the applied magnetic field, and even after the applied magnetic field is set to zero, the present invention can continuously generate a magnetic field larger than the applied magnetic field. We proposed a magnet device.

In this hybrid type bulk superconducting magnet device, a bulk superconductor (magnetic lens unit) having different characteristics having a shape for converging a magnetic field is arranged at the inner center of a cylindrical bulk superconductor, and magnetized externally. By magnetizing a cylindrical bulk superconductor (cylindrical part) with a superconducting magnet for magnetism, a magnetic field higher than the magnetic field captured only by the cylindrical bulk superconductor can be generated in the inner center. Even after the magnetic field application is set to zero, a magnetic field larger than the applied magnetic field can be continuously generated.

In Patent Document 2, as a combination of a cylindrical bulk superconductor and a bulk superconductor lens, a combination of a MgB ₂ bulk cylinder and a REBaCuO (RE is a rare earth metal element or Y) bulk lens and both are the same REBaCuO (RE is a rare earth metal element). Alternatively, a combination of a bulk cylinder consisting of Y) and a bulk lens is disclosed. Of these, the MgB ₂ bulk cylindrical magnet has low superconductivity, so the maximum generated magnetic field in this case is about 5 T, which is lower than the maximum generated magnetic field that can be realized by the conventional REBaCuO bulk cylindrical magnet. Is more advantageous to use. In that case, a magnetic field of about 13.5T can be realized in the bulk lens by magnetizing about 10T.

FIG. 2A shows a hybrid type superconducting bulk magnet device (hereinafter, also simply referred to as a superconducting bulk magnet device) 11 proposed by the present inventor in Patent Document 1. In this superconducting bulk magnet device 11, a bulk superconductor magnetic lens 12 formed by abutting a pair of superconducting bulks is arranged in the inner center of a cylindrical bulk superconductor 13, and a magnetizing superconducting magnet arranged outside. A magnetizing magnetic field (applied magnetic field _Bapp ) is applied by 14. As shown in FIG. 2A, the bulk superconductor magnetic lens 12 has a shape for converging a magnetic field, and its characteristics are different from those of the cylindrical bulk superconductor 13. For example, REBaCuO (RE is a rare earth element or Y) is used as the superconducting bulk of the bulk superconductor magnetic lens 12, and the same REBaCuO (RE is a rare earth element or Y) is used as the superconducting bulk of the cylindrical bulk superconductor 13. As the magnetizing superconducting magnet 14, for example, a solenoid type coil or a split type coil made of NbTi is used. As the REBaCuO, GdBaCuO and EuBaCuO are particularly preferable.

In this superconducting bulk magnet device 11, the cylindrical bulk superconductor 13 is magnetized by the magnetizing superconducting magnet 14, so that the magnetic field capture phenomenon by the cylindrical bulk superconductor 13 and the magnetic convergence by the bulk superconductor magnetic lens 12 by combining effect, as shown in FIG. 2 (b), the applied magnetic field B _app to generate a large magnetic field B _c from and from applied magnetic field B _app after the zero magnetic field applied by magnetizing the superconducting magnet 14 A large magnetic field B _c can be continuously generated.

As shown in FIG. 3 in FIG. 3, the superconducting bulk magnet device 11 is extremely compact and is suitable for applications in which a large magnetic field is generated in a relatively small space.

In the magnetization process of the superconducting bulk magnet device 11 of this example, the GdBaCuO cylinder 13 is _{maintained at a temperature higher than the superconducting transition temperature T c} = 92K during the magnetizing process, and the GdBaCuO lens 12 is kept at a temperature lower than the _{superconducting transition temperature T c = 92K.} Be cooled. GdBaCuO lens 12 by increasing the external magnetic field _{B ex} is magnetized by zero-field cooling (ZFC). Then, the temperature of GdBaCuO lens 12 and GdBaCuO cylinder 13 is reduced for example to 20K, by a reduction in the external magnetic field B _ex in about reduced磁過, GdBaCuO cylinder 13 is magnetized by the magnetic field during cooling magnetization (FCM), magnetic flux GdBaCuO cylindrical Captured within 13. Therefore, in the superconducting bulk magnet device 11, it is necessary to individually control the temperatures of the GdBaCuO lens 12 and the GdBaCuO cylinder 13.

Here, as a method of individually controlling the temperature of the GdBaCuO lens and the GdBaCuO cylinder, the following four methods can be considered.

As shown in FIG. 4A, the first method is a method in which the temperature of the GdBaCuO lens and the GdBaCuO cylinder is controlled by the cold stage of two independent cooling devices. However, although this method allows verification experiments, it cannot realize a wide room temperature magnetic field space, is not suitable for application, and has a drawback of being expensive.

In the second method, as shown in FIG. 4 (b), one cooling device is used, the cold stage is held at 20K, and the GdBaCuO cylinder is separated from the cold stage of the cooling device in the magnetizing process. In the demagnetization process, a mechanical heat switch is used to make thermal contact with the cold stage of the cooling device. However, this method has a drawback that it is technically difficult to realize what kind of good thermal contact is achieved in a magnetic field in a vacuum vessel, and it is expensive.

In the third method, as shown in FIG. 4 (c), one cooling device is used, a heater is provided between the cold stage of the cooling device and the GdBaCuO cylinder, and the temperature of the GdBaCuO cylinder is heated by the heater in the magnetizing process. Is a method in which T _c = 92K or more is set, and the heater is turned off in the demagnetization process to keep the temperature at 20K. However, this method has a drawback that the heat load is too large and it is practically difficult to maintain the cold stage of the cooling device at 20K.

In the fourth method, as shown in FIG. 4D, one cooling device is used, and a heat switch using He gas is provided between the cold stage of the cooling device and the GdBaCuO cylinder, and in the magnetizing process. This is a method in which the heat switch is vacuum-insulated to _{raise the temperature to T c} = 92K or higher, and in the demagnetization process, the heat switch is filled with He gas and held at 20K. However, this method has a drawback that it is not clear whether a He gas type thermal switch can be realized, and even if it can be realized, the device configuration becomes complicated.

As described above, as a method of individually controlling the temperature of the GdBaCuO lens and the GdBaCuO cylinder, all of the above four methods have the above-mentioned drawbacks and have a problem that it is difficult to realize.

Japanese Unexamined Patent Publication No. 2009-135487 (Patent No. 5158799) WO2019 / 42816 A1

Z. Y. Zhang et al., 2012 Supercond. Sci. Technol. 25 115012. K. Katagiri et al., Physica C 392-396 (2003) pp. 526-530.

The present invention solves the above-mentioned problems of the prior art, can generate a magnetic field larger than the applied magnetic field, and can continuously generate a magnetic field larger than the applied magnetic field even after the applied magnetic field is set to zero. A hybrid superconducting bulk magnet device and its magnetizing method that can reliably and individually control the temperatures of a cylindrical bulk superconductor and a bulk superconductor lens made of the same material with a single cooling device at low cost. The challenge is to provide.

According to the present invention, the following inventions are provided in order to solve the above problems.
[1] A pair of superconducting bulks having a shape for converging a magnetic field at the inner center of a cylindrical bulk superconductor made of REBaCuO (RE is a rare earth element or Y) and made of the same material as the cylindrical bulk superconductor. By arranging a bulk superconductor magnetic lens that is abutted against each other and magnetizing the cylindrical bulk superconductor with a magnetizing superconducting magnet installed outside, the phenomenon of capturing a magnetic field by the cylindrical bulk superconductor and the above-mentioned Combined with the magnetic convergence effect of the bulk superconductor magnetic lens, a magnetic field larger than the applied magnetic field is generated, and even after the magnetic field application by the magnetizing superconducting magnet is made zero, the captured magnetic field remaining in the cylindrical bulk superconductor. A hybrid superconducting bulk magnet device capable of continuously generating a magnetic field larger than the applied magnetic field, and one cooling device for cooling the cylindrical bulk superconductor and the bulk superconductor magnetic lens. A heat leak member is provided between the cooling device and the cylindrical bulk superconductor to delay the cooling of the cylindrical bulk superconductor with respect to the cooling of the bulk superconductor magnetic lens, and the cylindrical bulk superconductor is provided. A hybrid type superconducting bulk magnet device characterized in that the temperatures of the body and the bulk superconductor magnetic lens are individually controlled.
[2] The hybrid type superconducting bulk magnet device according to the first invention, wherein the heat leak member is a fiber reinforced plastic.
[3] The hybrid superconducting bulk magnet apparatus according to the first or second invention, wherein the cylindrical bulk superconductor and the bulk superconductor magnetic lens are made of GdBaCuO.
[4] The hybrid superconducting bulk magnet apparatus according to the first or second invention, wherein the cylindrical bulk superconductor and the bulk superconductor magnetic lens are made of EuBaCuO.
[5] In any of the inventions [1] to [4], the hybrid is characterized in that mechanical reinforcing members are provided around the cylindrical bulk superconductor and the bulk superconductor magnetic lens, respectively. Type superconducting bulk magnet device.
[6] Using the hybrid type superconducting bulk magnet device according to any one of the above [1] to [5], the cylindrical bulk superconductor is maintained in a normal conducting state during the magnetizing process, and the bulk superconductor is maintained. The magnetic lens is placed in a superconducting state, the external magnetic field generated by the magnetizing superconducting magnet is linearly increased, the bulk superconductor magnetic lens is magnetized by zero magnetic field cooling, and then the cylindrical bulk superconductor and the bulk superconductor are magnetized. Both body magnetic lenses are placed in a superconducting state, and in the demagnetization process, the external magnetic field generated by the magnetizing superconducting magnet is linearly reduced while maintaining the superconducting states of the cylindrical bulk superconductor and the bulk superconductor magnetic lens. The cylindrical bulk superconductor is cooled and magnetized in a magnetic field, the magnetic flux is captured by the cylindrical bulk superconductor, and even after the application of the external magnetic field is stopped, a magnetic field larger than the applied magnetic field is continuously generated. A featured method of magnetizing a hybrid superconducting bulk magnet device.

According to the present invention, since the above configuration is adopted, a magnetic field larger than the applied magnetic field can be generated, and even after the applied magnetic field is set to zero, a magnetic field larger than the applied magnetic field can be continuously generated, and To provide a hybrid superconducting bulk magnet device capable of reliably and individually controlling the temperatures of a cylindrical bulk superconductor made of the same material and a bulk superconductor lens at a low cost and a magnetizing method thereof with one cooling device. Is possible.

The hybrid superconducting bulk magnet device of the present invention includes environmental purification fields such as magnetic separation that separates harmful substances by magnetic force, energy fields such as small and high-efficiency motors and generators, and medical treatment such as nuclear magnetic resonance (NMR) devices. It can be used in fields. It can also be applied to measurement and high energy physics fields such as "separation and purification of substances" and "electron / ion beam convergence", which were not possible with conventional superconducting bulk magnet devices.

According to the present invention, there is a possibility that a strong magnetic field of 15T class can be continuously realized relatively easily by using hundreds of 10T superconducting magnets installed in Japan, and this merit and impact are great.

(A) is a diagram showing an example configuration of a superconducting magnet device using a conventional bulk superconductor magnetic lens, and (b) is a diagram showing the relationship between an external magnetic field and a magnetic field generated in the bulk superconductor lens by its application. is there. The figure which shows the structure of an example of the hybrid type superconducting bulk magnet apparatus proposed by the present inventor in Patent Document 2, (b) is the figure which shows the relationship between the external magnetic field and the magnetic field generated in the bulk superconductor lens by the application thereof. .. It is a figure which shows the dimensional example of each part of the hybrid type superconducting bulk magnet apparatus which the present inventor proposed in Patent Document 2. It is explanatory drawing for demonstrating four methods usually considered for controlling the temperature of a cylindrical bulk superconductor and a bulk superconductor lens individually in the said hybrid type superconducting bulk magnet. It is a figure which shows typically the structure of the hybrid type superconducting bulk magnet apparatus which concerns on one Embodiment of this invention. (A) is a diagram showing the time sequence of the hybrid type bulk magnet device according to the above embodiment, and is a diagram showing the relationship between the external magnetic field of (b) and the magnetic field generated in the bulk superconductor lens by the application thereof. It is a figure which shows the magnetic field distribution on the central axis (x-axis) in a magnetizing process and demagnetizing process. B _app = 3T, 6T, a diagram showing the relationship between the external magnetic field _{B ex} and the generated magnetic field (center field) _{B c} in each step (step 0-10) in the case of 10T. It is a figure which shows the temperature dependence of the thermal conductivity κ of various materials. It is a figure which shows the temperature distribution at 300K and 200K of a GdBaCuO lens and a GdBaCuO cylinder when a fiber reinforced plastic (FRP) is inserted as a heat leak plate between a GdBaCuO cylinder and a cold stage of a cooling device. It is a figure which shows the time dependence of the temperature change of a GdBaCuO lens and a GdBaCuO cylinder when a fiber reinforced plastic (FRP) is inserted as a heat leak plate between a GdBaCuO cylinder and a cold stage of a cooling device. It is a figure which shows the temperature distribution at 300K and 200K of a GdBaCuO lens and a GdBaCuO cylinder when a stainless steel plate is inserted between a GdBaCuO cylinder and a cold stage of a cooling device. It is a figure which shows the time dependence of the temperature change of a GdBaCuO lens and a GdBaCuO cylinder when a stainless steel plate is inserted between a GdBaCuO cylinder and a cold stage of a cooling device. It is a figure which shows the time dependence of the center temperature of the GdBaCuO lens 22 and the GdBaCuO cylinder 23 using various heat leak materials. It is a figure which shows the heat leak plate thickness dependence of the cooling rate when the heat leak material is a fiber reinforced plastic (FRP (G10 (normal))).

Hereinafter, the present invention will be described in detail based on the embodiments.

FIG. 5 schematically shows the configuration of a hybrid type superconducting bulk magnet device (hereinafter, also simply referred to as a superconducting bulk magnet device) 21 according to an embodiment of the present invention. In this superconducting bulk magnet device 21, a bulk superconductor magnetic lens 22 formed by abutting a pair of superconducting bulks is arranged in the inner center of a cylindrical bulk superconductor 23, and a magnetizing superconducting magnet arranged outside. A magnetic field for magnetizing (applied magnetic field _Bapp ) is applied by 24. Although the bulk superconductor magnetic lens 12 is schematically shown as a block in FIG. 6, it is actually shaped to converge the magnetic field as shown in FIGS. 2 (a) and 3 (a). The characteristics are different from those of the cylindrical bulk superconductor 23. The bulk superconductor magnetic lens 22 has slits formed as shown in the lower view of FIG. 3 as a plan view, and the presence of these slits plays an important role in producing the magnetic lens effect. ing. For example, REBaCuO (RE is a rare earth element or Y) is used as the superconducting bulk of the bulk superconductor magnetic lens 22, and REBaCuO, which is the same material as the bulk superconductor magnetic lens 22, is also used as the superconducting bulk of the cylindrical bulk superconductor 23. (RE is a rare earth element or Y) is used, and as the magnetizing superconducting magnet 24, for example, a solenoid type coil or a split type coil made of NbTi is used. As the REBaCuO, GdBaCuO and EuBaCuO are particularly preferable.

The superconducting bulk magnet device 21 is provided with one cooling device 25, and a disk-shaped heat leak plate 26 made of a low thermal conductivity material is arranged between the cold stage and the lower surface of the cylindrical bulk superconductor 23. Has been done. The heat leak plate 26 plays a role of delaying the cooling of the cylindrical bulk superconductor 23 with respect to the cooling of the bulk superconductor magnetic lens 22, and separately sets the temperatures of the cylindrical bulk superconductor 23 and the bulk superconductor magnetic lens 22. It can be controlled. As the heat leak plate 26, an appropriate material can be used as long as it is a low thermal conductivity material that delays the cooling of the cylindrical bulk superconductor 23 for a certain period of time with respect to the cooling of the bulk superconductor magnetic lens 22, but for example, fibers. Reinforced plastic (FRP), epoxy resin and the like are preferably used. The cooling rate by the heat leak plate 26 can be controlled by appropriately setting the thermal conductivity, thickness, and cross-sectional area depending on the material. Hereinafter, the bulk superconductor magnetic lens using GdBdCuO may be abbreviated as GdBdCuO lens, and the cylindrical bulk superconductor using GdBdCuO may be abbreviated as GdBdCuO cylinder. Then, the GdBdCuO lens and the GdBdCuO cylinder will be mainly described.

In this superconducting bulk magnet device 21, as shown in FIG. 5, mechanical reinforcing members 27 are provided around the bulk superconductor magnetic lens 22 and the cylindrical bulk superconductor 23, respectively. The fracture strength of the REBaCuO bulk is about 50 to 70 MPa (Non-Patent Document 2). For example, in the case of a BaGdCuO cylinder, fracture does not occur at an applied magnetic field of 3T, but at an applied magnetic field of 10T, a tension of 200 MPa or more is applied to the inner wall of the end face of the BaGdCuO cylinder. Stress is applied. Further, in the case of a BaGdCuO lens, a compressive stress of up to 50 MPa is applied at an applied magnetic field of 10 T, and a positive / negative stress distribution is generated by the applied magnetic field in the lens. Therefore, the mechanical reinforcing member 27 is provided. As the mechanical reinforcing member 27, an alloy having high thermal conductivity and high strength, such as stainless steel (SUS), can be used.

The bulk superconductor magnetic lens 22 and the cylindrical bulk superconductor 23 of the superconducting bulk magnet device 21 of the present embodiment can have the shape and size shown in FIG. 3, for example.

The magnetization process of the superconducting bulk magnet device 21 of the present embodiment takes the time sequence of FIGS. 6 and (1) to (5) shown below. B _app is 10T.

(1) GdBaCuO cylinder 23 is maintained at 100K, GdBaCuO lens 22 is cooled to _T H = 40K. Therefore, at this stage, the GdBaCuO cylinder 23 is in the normal conducting state, and the GdBaCuO lens 22 is in the superconducting state (step 0).

(2) an external magnetic field _{B ex} increases linearly over 5 steps until _{B app} (step 1 to _{5), B app} equal magnetic field completely through GdBaCuO cylinder 23, the magnetic field is converged to the center of the magnetic lens However, the GdBaCuO lens 22 is magnetized by zero magnetic field cooling (ZFC).

(3) The temperature of both the GdBaCuO cylinder 23 and the GdBaCuO lens 22 _{drops to TL} = 20K.

(4) The external magnetic field _Bex decreases linearly and becomes 0 in 5 steps (steps 6 to 10). During this process, the GdBaCuO cylinder 23 is magnetized by cooling in a magnetic field (FCM) and the magnetic flux is captured within the GdBaCuO cylinder 23. Field focusing effect is slightly decreased due to a decrease of the external magnetic field B _ex, because of the presence of the magnetic field trapped GdBaCuO cylinder 23, the center magnetic field B _c in the center of GdBaCuO lens 22 is still.

(5) As a result, as shown in FIG. 6B, a superconducting bulk magnet device capable of reliably generating a magnetic field B _{c higher than Bapp is realized even after the external magnetic field Bex = 0.}

FIG. 7 shows the magnetic field distribution on the central axis (x-axis) in the magnetizing process and the demagnetizing process.

Further, in FIG. 8 _shows B app = 3T, 6T, the relationship between the external magnetic field _{B ex} and the generated magnetic field (center field) _{B c} in each step in the case of 10T (step 0-10). In each case, the magnetic field could be continuously generated even after the application of the magnetic field was stopped. Further, to the Table _{1, B app (T),} B T (T), B c (T), a summary of the data of the _{B c /} B _app.

Here, the heat leak plate 25, which is a major feature of the superconducting bulk magnet device 21 of the present embodiment, will be described in more detail.

In this superconducting bulk magnet device 21, as shown in FIG. 6A, in the magnetizing process (steps 1 to 5), the GdBaCuO cylinder 23 undergoes a zero magnetic field cooling (ZFC) magnetizing process when the GdBaCuO lens 22 is 20K. The material (thermal conductivity), thickness, and cut of the heat leak plate 25 are slowly cooled so that the temperature (for example, Tc = 100K) is higher than the superconducting transition temperature (T _{c = 92K) during the process.} The area can be estimated in advance by simulation.

FIG. 9 shows the temperature dependence of the thermal conductivity κ of various materials, that is, fiber reinforced plastic (FRP (G10)), Al alloy (A7075), stainless steel (SUS304), indium (In), and copper (Cu). .. From FIG. 9, it can be seen that the thermal conductivity of the fiber reinforced plastic (FRP (G10)) is about an order of magnitude smaller than that of stainless steel (SUS304).

As an example, a fiber reinforced plastic (FRP) plate (thermal conductivity at 300K: 1.7 W / mK; thickness () mm, diameter) as a heat leak plate 26 between the GdBaCuO cylinder 23 and the cold stage of the cooling device 25. The temperature distribution of the GdBaCuO lens 22 and the GdBaCuO cylinder 23 at 300K and 200K when () mm) is inserted and cooled from 300K to 20K is shown in FIG. 10, and the time dependence of the temperature change is shown in FIG.

As can be seen from FIG. 11, the GdBaCuO lens 22 reaches 20K in 4000s, while the GdBaCuO cylinder 23 is 100K or more even in 10000s due to the presence of the heat leak plate (fiber reinforced plastic (FRP)) 26. In this case, if the GdBaCuO lens 22 in the first half of the sequence is subjected to zero magnetic field cooling (ZFC) between 4000s and 10000s, then the GdBaCuO cylinder 23 has passed a sufficient time and reaches 20K, and then the GdBaCuO cylinder in the latter half of the sequence. Cooling magnetization (FCM) in a magnetic field of 23 may be performed.

By controlling the cross-sectional area and thickness of the fiber reinforced plastic (FRP) plate constituting the heat leak plate 26, it is possible to control the cooling delay of the GdBaCuO cylinder 23. It is also possible to control the material of the plate by using a material other than fiber reinforced plastic (FRP).

For comparison, a stainless steel plate (thermal conductivity: 15 W / mK; thickness () mm, diameter () mm)) is inserted between the GdBaCuO cylinder 23 and the cold stage of the cooling device 25, from 300K to 20K. FIG. 12 shows the temperature distribution of the GdBaCuO lens 22 and the GdBaCuO cylinder 23 when cooling, and FIG. 13 shows the time dependence of the temperature change.

As can be seen from FIG. 13, the cooling of the GdBaCuO cylinder 23 is delayed due to the presence of the stainless steel (SUS304) plate, but the difference is slight. In this case, the delay effect is not as great as the effect of inserting the fiber reinforced plastic (FRP) plate.

FIG. 14 shows the time dependence of the center temperature of the GdBaCuO lens 22 and the GdBaCuO cylinder 23 using various heat leak materials (thickness 5 mm, diameter 5 mm). In this case, a stainless steel (SUS304) plate was inserted between the GdBaCuO lens 22 and the cold stage of the cooling device 25. As various heat leak materials, fiber reinforced plastic (FRP (G10 (normal))), fiber reinforced plastic (FRP (G10 (warp))), epoxy resin, and stainless steel (SUS304) were used. From FIG. 14, it can be seen that the time dependence of the center temperature of the GdBaCuO lens 22 and the GdBaCuO cylinder 23 differs greatly depending on the material of the heat leak material.

FIG. 15 shows the heat leak plate thickness dependence of the cooling rate when the heat leak material is fiber reinforced plastic (FRP (G10 (normal))). The thickness of the heat leak plate was 3 mm, 5 mm, 10 mm, 15 mm, and 20 mm. From FIG. 15, it can be seen that the cooling rate of the heat leak plate largely depends on the thickness of the heat leak plate.

In consideration of the data shown above, the material (thermal conductivity), thickness, and cross-sectional area of the heat leak plate 26 can be set so as to be able to appropriately control the temperature.

In the superconducting bulk magnet device 21 of the present invention, a disk-shaped heat leak plate 26 made of a low thermal conductivity material is arranged (inserted) between the cold stage of the cooling device 25 and the lower surface of the cylindrical bulk superconductor 23. The temperature of the GdBaCuO lens 22 and the GdBaCuO cylinder 23 can be controlled easily and inexpensively with one cooling device, and an open space can be realized.

21 Superconducting bulk magnet device 22 Bulk superconductor magnetic lens 23 Cylindrical bulk superconductor 24 Magnetizing superconducting magnet 25 Cooling device 26 Heat leak plate 27 Mechanical reinforcement member

Claims (6)

A pair of superconducting bulks made of the same material as the cylindrical bulk superconductor, which has a shape for converging a magnetic field, are butted against the inner center of a cylindrical bulk superconductor made of REBaCuO (RE is a rare earth element or Y). By arranging a bulk superconductor magnetic lens and magnetizing the cylindrical bulk superconductor with a magnetizing superconducting magnet installed outside, the magnetic field capture phenomenon by the cylindrical bulk superconductor and the bulk superconductor Combined with the magnetic convergence effect of the magnetic lens, a magnetic field larger than the applied magnetic field is generated, and even after the magnetic field application by the magnetizing superconducting magnet is reduced to zero, it is applied by the captured magnetic field remaining in the cylindrical bulk superconductor. A hybrid superconducting bulk magnet device that can continuously generate a magnetic field larger than the magnetic field.
A cooling device for cooling the cylindrical bulk superconductor and the bulk superconductor magnetic lens is provided, and the bulk superconductor magnetic lens is cooled between the cooling device and the cylindrical bulk superconductor. On the other hand, a hybrid superconducting bulk magnet apparatus characterized in that a heat leak member for delaying the cooling of the cylindrical bulk superconductor is arranged and the temperatures of the cylindrical bulk superconductor and the bulk superconductor magnetic lens are individually controlled. .. The hybrid type superconducting bulk magnet device according to claim 1, wherein the heat leak member is a fiber reinforced plastic. The hybrid superconducting bulk magnet device according to claim 1 or 2, wherein the cylindrical bulk superconductor and the bulk superconductor magnetic lens are made of GdBaCuO. The hybrid superconducting bulk magnet device according to claim 1 or 2, wherein the cylindrical bulk superconductor and the bulk superconductor magnetic lens are made of EuBaCuO. The hybrid superconducting bulk magnet device according to any one of claims 1 to 4, wherein mechanical reinforcing members are provided around the cylindrical bulk superconductor and the bulk superconductor magnetic lens, respectively. Using the hybrid superconducting bulk magnet device according to any one of claims 1 to 5,
In the magnetizing process, the cylindrical bulk superconductor is maintained in a normal conducting state, the bulk superconductor magnetic lens is placed in a superconducting state, and the external magnetic field generated by the magnetizing superconducting magnet is linearly increased to linearly increase the bulk superconductor. After magnetizing the magnetic lens by zero magnetic field cooling, both the cylindrical bulk superconductor and the bulk superconductor magnetic lens are placed in a superconducting state.
In the demagnetization process, the external magnetic field generated by the magnetizing superconducting magnet is linearly reduced while maintaining the superconducting state of the cylindrical bulk superconductor and the bulk superconductor magnetic lens, and the cylindrical bulk superconductor is subjected to a magnetic field. It is medium-cooled and magnetized, and the magnetic flux is captured by the cylindrical bulk superconductor.
A method of using a hybrid superconducting bulk magnet device, characterized in that a magnetic field larger than the applied magnetic field is continuously generated even after the application of the external magnetic field is stopped.

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